Quark Gluon Plasma Science The Path to Complete the Mission

Jamie Nagle (University of Colorado) Kitty Hawk, North Carolina NP Long Range Plan Resolution Meeting, April 16-20, 2015

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Hot QCD Physics in 2007

Perfect Liquid?

Ideal hydrodynamics, smooth initial conditions, elliptic flow only, qualitative statement on perfect fluidity

First discovery stage QGP observations

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The world has changed since 2007

• Quantum fluctuations in the Initial State • 2nd Order, 3-Dimensional, Relativistic Viscous Hydrodynamics

• Precision Lattice Equation of State • RHIC and LHC precision measures of higher moments

...)](5cos[2)](4cos[2)](3cos[2)](2cos[21 55443322 +Ψ−+Ψ−+Ψ−+Ψ−+= φφφφφ

vvvvddN

η/s=1.5/4π η/s=2.5/4π

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Quantitative Constraints

Using latest climate / cosmology techniques, multi-variate analysis on RHIC & LHC data.

Experimental confirmation of QCD Equation of State!

Temperature [MeV]

(Spe

ed o

f Sou

nd)2

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Resolving sub-nucleonic quantum structure

Key Electron Ion Collider question… Initial gluonic state – strongly or weakly coupled?

RHIC Geometries Enable Probes of Initial State

Gluon density fluctuations

gluon saturation IP-Glasma

U+U

Au+Au

Nucleon density fluctuations

Glauber

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Discovery at LHC high multiplicity p+p/p+A

Collective-Like Patterns

Hot Topic

RHIC 3He+Au

RHIC as the world’s most versatile collider is now engineering the

droplet geometry (1,2,3)

Remarkable RHIC verification of small QGP hydrodynamics

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• Enabled by RHIC luminosity upgrade (x20) • Enabled by RHIC extending energy range 7-200 GeV (x26) • Enabled by LHC extending energy range to 2.76 TeV (x14) • Major advances in quantitative modeling and theory

PHENIX STAR RHIC

LHC CMS

ALICE

Impressive Strides in QGP Understanding

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Emergent Phenomena Connection from the QCD Lagrangian to phenomena of confinement and asymptotic freedom was fundamental

Connection from QCD to the emergent phenomena of near perfect fluidity of the Quark-Gluon Plasma near the phase transformation is just as fundamental

Pinning down η/s tells us the nature of the QGP, more importantly we need to reconcile:

Most important discovery in field: perfect fluid

& Crucial part of QCD: weak coupling at short distances

9 9 BEScan-2

LHC Run 2

LHC Run 3

Pb+Pb Pb+Pb/p+Pb

Pb+Pb/p+Pb/Ar+Ar

ALICE Upgrade LHC Luminosity

2020-2023

Heavy Flavor Physics

The Plan for Continued Progress in our Understanding

Relativistic Heavy Ion Collider Large Hadron Collider

2014-2016

2019-2020

2021-2022

Much more detail in RHIC Facilities Talk…

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Buoys (Heavy Quarks) in the Plasma

Charm – Anticharm Pairs Drag/Diffuse in Perfect Fluid

Heavy Flavor Physics

2014-2016

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Heavy Quarks Flow

Charm precision data RHIC – 2014-2016

LHC – ALICE upgrades 2020-23

Models require strongest coupling near Tc

Precision data to extract QGP drag coefficients

• US Expertise at RHIC applied at LHC

• US Leadership Roles

LHC – ALICE upgrades 2020-23

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Doping the QGP with Quarks

Lower collision energies yield QGP with larger baryon

chemical potential (µB)

2007 - priority to have pilot Beam Energy Scan

Energies Run: 7.7, 11.5, 14.5, 19.6, 27,

39, 62, 200 GeV

What did we learn?

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Not just a cartoon anymore

• Trajectories – hydrodynamic model constrained by data • Red points – measured hadronic freeze-out points • Confirmed that all energies have droplets in QGP phase • Lattice QCD indicates if Critical Point exists, µB > 200 MeV

14 BES-2 Data Taking 2019-2020

Critical Point Hints Minimum in v1 slope was

predicted as consequence of the softening of the equation of

state in the transition region.

Net-proton fluctuations, proximity to critical point?

Possible Scenario Near Critical Point

RHIC electron cooling 20 year program 2 years

Precision Search for Critical Point

BES-2 Data Taking 2019-2020

BES-2 Projection Luminosity (cm-2sec-1)

√sNN (GeV) 15

Leading hadron

Leading hadron

Photons

Jet Quenching Discovery Precision

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LHC – Reconstructed Jets

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Jet Probes of QGP Structure

Parton virtuality evolves quickly and is influenced by the

medium at the scale it probes

Thick lines indicate where the QGP

influences virtuality evolution

RHIC Jet Probes LHC Jet Probes QGP Influence

Bare Color Charges

Thermal Mass Gluons

Perfect Fluid Only

Unique critical microscope resolution

at RHIC.

Measurement overlap between RHIC and LHC

very important too.

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A New Detector at RHIC

High data acquisition rate capability, 15 kHz

Sampling 0.6 trillion Au+Au interactions in one-year Maximizing efficiency of RHIC running

BaBar Magnet 1.5 T

Coverage |η| < 1.1

All silicon tracking Heavy flavor tagging

Electromagnetic Calorimeter

Hadronic Calorimeter

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Jet probe precision data RHIC – 2021-2022 LHC – 2020-2023

Precision Imaging of QGP Over Key Kinematics

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Strongest coupling near Tc as Perfect Fluid Emerges

pQCD αs running, are probes weakly

coupled at all scales?

Jet – Medium Interactions

Coup

ling

Stre

ngth

γ

q

Photon-Tagged Jets

Golden channel where photon calibrates quark

γ (E=20 GeV), S/B is 20x better at RHIC Underlying event 2.5x smaller

Equark

Ephoton

sPHENIX unique mapping of path (L) dependence of parton-QGP interactions.

Key to resolving strongest coupling near transition temperature and why.

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Beauty Quark

Forward radiation suppressed, dead-cone.

Key handle on what is being scattered from in medium

Beauty-Tagged Jets

EIC will test parton energy loss in cold nuclear matter,

and with specific tag on virtuality (charm quarks too)!

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Precision Imaging via Very Heavy Quarkonia

Mapping out Temperature dependence of

plasma screening

Υ(1s) should melt at LHC, but not at RHIC!

Upsilon precision data sPHENIX – 2021-2022

CMS – 2020-2023

Color Screening

ccb b

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Theory None of this would be possible (past, present, future)

without enormous advances in theory !

Many examples abound…

• 3-D Relativistic Viscous Hydrodynamics • Detailed lattice QCD Equation of State • Gluon saturation initial conditions • AdS/CFT pre-equilibrium calculations • Langevin drag / diffusion for heavy quarks • Lattice QCD for extraction of T, µB • Perturbative parton-QGP interactions [JET Topical Collaboration] • AdS/CFT strong coupling heavy quark calculations • Lattice QCD pushed to finite µB • Chiral Magnetic Effect embedded in hydrodynamics • Heavy quark recombination in full space-time evolution

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RHIC

1) With low-energy cooling, RHIC is the best tool we will have in our lifetimes to explore experimentally

the phase diagram of QCD.

2) With sPHENIX, RHIC is the best tool we will have in our lifetimes to explore experimentally the

most perfect liquid ever created.

LHC

3) Enormous leverage for US of expertise and synergy of techniques and detector work between

RHIC and LHC. Highest T and smallest scale probes.

Perfect Liquid?

2007

2015 A mature field… An informed view of the key remaining questions and how to top out.

For the detailed path to deliver this key physics,

wait for the RHIC facilities and EIC talks

tomorrow

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Recommendations from the Hot QCD Community

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Recommendations from the Hot QCD Community

Backup Material

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Emergent Phenomena

Discovery of QGP as perfect fluid was huge!

We know a lot about how QGP behaves,

but not so much about how it really works.

Discovery of High Tc Superconductors was huge!

However, we still do not know what really

carries the charge.

Now it is critical to probe QGP (High Tc Superconductors) at different length scales and

change the net baryon density (doping) to get full insight.

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A+A collisions release thousands of virtual gluons

from the nuclear wavefunction “The Hammer”

p+A may in fact be a mini-hammer

A+A

p+A

e+A Electron-Ion Collider • Tickling the nucleus

• Individual hard kicking of partons or scattering from collective gluonic matter

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RHIC-II performance is here!

Unfortunate that because RHIC did it 3 years earlier and for 1/7 the cost,

there are no fireworks…

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Expect η/s to increase at higher temperatures even just from running of αs

Now underway, full inclusion of fluctuations (v3, v4, v5, …). We know this rules out many initial condition scenarios

QGP Temperature Dependence

Critical Knobs to Turn

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Can we observe the strongest coupling near Tc definitively

What are the inner workings?

(quasiparticles, fields, modes)

How do the parton shower and medium

evolve together?

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Less J/ψ suppression at LHC with higher temperature

Charm recombination dominant effect, not screening.

Color conductivity in QGP!

Heavy Quarkonia Recombination

C C

J/ψ Suppression

RHIC

LHC

Look to Upsilons for Debye Screening,

no recombination at RHIC

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Laboratory Microscopes PHENIX STAR RHIC

LHC CMS

ALICE

Is sPHENIX a must have microscope? Aren’t there already a lot of microscopes?

Key answers about the emergence of

perfect fluidity in the region of strongest coupling and with focus on the transition scales,

in temperature and length, will be lost without this new microscope at RHIC.

With such a powerful accelerator at RHIC,

U.S. is well placed to maintain leadership and new discovery potential.

QGP Constituent Mass Dependence

Limit of infinitely massive scattering centers yields all

radiative e-loss.

Medium parton

qhat scattering of leading parton radiation e-loss ehat energy transferred to the QGP medium

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q scattering of leading parton which then radiates

e energy transfer from parton to QGP particle

^ ^

Collisional Radiative

Probing different length scales

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What sets this scale? – the exchange gluon

momentum? – total coherent energy

loss? – impact of

deconfinement?

1/λ Do the highest energy jets at LHC see

point-like color charges?

Do the lowest energy jets at RHIC scatter

from coherent fields or only excite sound

waves?

Deeper Connections

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21

21

EEEEAJ +

−=

RHIC and LHC Leverage

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Expect η/s to increase at higher temperatures even just from running of αs

Now underway, full inclusion of fluctuations (v3, v4, v5, …). We know this rules out many initial condition scenarios

QGP Temperature Dependence

Initial Condition favors larger ellipticity, more damping

Initial Condition favors smaller ellipticity, less damping

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Using Coleman-Smith’s dijet asymmetry the effective coupling is varied, how well can our projected measurement for 35 GeV jets

with R = 0.3 constrain this parameter.

Of course, many observables need to be included since there is more than one unknown. The key is over-constraining the problem.

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“Jet Quenching is a few times stronger near Tc relative to the

QGP at T > Tc.” Liao and Shuryak, PRL (2009)

“The surprisingly transparent sQGP at the LHC [compared to RHIC]”

Horowitz and Gyulassy, NPA (2011)

“Large v2 is striking in that it exceeds expectations of pQCD

models even at 10 GeV/c.” PHENIX, PRL (2010)

Super-Strong Coupling near Tc?

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Chiral Magnetic Effect Signature

Topological domains with QGP chiral symmetry restoration Effect goes away when chiral symmetry is no longer restored

BES-2 Data Taking 2019-2020

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Some QGP signatures go away in less dense collisions

Large system exhibits some QGP behavior even at the

lowest energies

Low η/s QGP phase transfers fluctuations from the initial

overlap density into final-state

Lower temperature, less QGP to create triangular flow

Less QGP, More Hadronic Phase

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RHIC Jet Probes LHC Jet Probes QGP Influence

RHIC Jet Probes LHC Jet Probes QGP Influence

Reso

lutio

n [1

/fm

]

Parton virtuality evolves quickly and is influenced by the

medium at the scale it probes

Thick lines indicate where the QGP significantly influences

virtuality evolution

Bare Color Charges

Thermal Mass Gluons

Perfect Fluid Only

Critical microscope resolution at RHIC.

Also, overlap between RHIC and LHC for

simultaneous description.